1. Field of the Invention
The present invention relates to a digital information processing apparatus which digitally executes various processes. More particularly, the present invention pertains to a digital information processing apparatus which has multiple CPUs.
2. Description of the Related Art
Conventionally, various electronic apparatuses are digitized or computerized, and processing circuits have been developed for use in these apparatuses.
For example, in the field of electronic musical instruments, computerization has become common. A tone generating process which requires high-speed processing of a vast amount of data, however, is executed by a specially-designed hardware called a "tone generating circuit". A microcomputer in each electronic musical instrument simply processes control inputs to a musical instrument, such as input through a keyboard or a console panel, control input from an MIDI or other external units, input from an internal or external play memory, and sends a proper command to the tone generating circuit.
There are several problems in the system architecture of such an electronic musical instrument where tone generation is executed by the hardware-based tone generating circuit and processing of control inputs to the musical instrument is executed by the microcomputer. First of all, the hardware-based tone generating circuit is relatively large because the circuit needs a storage device, which temporarily stores data, and an arithmetic operation circuit wherever necessary in various stages for processing musical tone parameters. Secondly, a significant change often becomes inevitable in altering the design of the hardware-based tone generating circuit, thus requiring an enormous amount of time and effort for development of the circuit. Further, the interface between the microcomputer and the hardware-based tone generating circuits should be reviewed for every tone generating circuit, and be redeveloped.
For the above-described reasons, there has been proposed a digital information processing apparatus for an electronic musical instrument which can generate musical tones only by a microcomputer controlled by a program, not using any hardware-based tone generating circuit (U.S. patent application Ser. No. 455,978 filed on Dec. 22, 1989).
According to the embodiment of the above application, a single CPU executes a program to generate musical tones. In this case, the processing speed of the CPU needs to be increased to improve the performance of generating musical tones. Since the processing speed of the CPU is restricted by the limited operation speed of a semiconductor device used in the CPU, however, the realizable performance to generate musical tones is limited accordingly.
The forgoing description has been given with reference to an electronic musical instrument, for example, but the same shortcomings may arise in other various types of electronic apparatuses for processing digital information.